In many environments where people use computers, their computer display may be visible to other users. This can be a significant problem when the displayed information is private, restricted, or sensitive.
For example, doctors and other healthcare workers routinely display patients' private healthcare information on computer monitors in hospitals, clinics, and doctors' offices. With the migration of medical records to digital form, including the use of Electronic Medical Records systems (EMR), this practice is only set to increase.
A doctor using a computer to view his patient's healthcare information at a nursing station may be authorized to view that information. However, other doctors and healthcare workers at the nursing station, unassociated with the patient, may not be authorized to view that same private information, or some portions of the patent's information. Laws such as HIPAA require that the privacy of healthcare information be protected, and significant penalties can be incurred for failing to do so.
Therefore, a problem arises of restricting data to only authorized users, when such data is only obtainable or useful in a public, or semi-private setting. This problem extends beyond the medical field to other situations in which private, restricted, or sensitive information may be viewed on computers. For example, financial, or other confidential information might be displayed at inopportune times and locations in an office, showroom or factory.